Chemical composition of aerosols of novel tobacco- and nicotine-containing products such as tobacco heating systems requires a systematic study, being a starting point in assessing their level of risk to consumers. Carbon monoxide, benzene, benzo[a]pyrene, 1,3-butadiene, tobacco-specific nitrosamines NNN and NNK, acrolein, acetaldehyde, formaldehyde are included in the lists of priority tobacco smoke toxicants by WHO and various public health organizations, so their quantification in aerosols of novel products is an important step in determining both the absolute and relative (compared to cigarette smoke) product risk, taking into account mode of consumption and design features of these products. Levels of above mentioned toxic compounds were measured in aerosol of tobacco heating systems and in cigarette smoke by the high-performance liquid chromatography with mass spectrometry (HPLC/MS-MS) and gas chromatography with mass spectrometry (GS/MS) in the laboratory of chemistry of the All-Russian Scientific Research Institute of Tobacco, Makhorka and Tobacco Products. The results demonstrate that the levels of toxic compounds in the aerosol of the tested samples of tobacco heating systems are significantly (by 87–99%) lower than in the 3R4F reference cigarette smoke and the smoke of commercially available cigarettes. This can be explained by specific mechanism of aerosol formation in novel products without pyrolytic and pyrosynthetic reactions. Unlike cigarettes, where combustion is the principle of operation leading to smoke generation, tobacco heating systems form an aerosol without combustion by heating a substrate (tobacco mixture), to evaporate aerosol forming compounds such as glycerine and propylene glycol, along with nicotine and flavour compounds. Nicotine content in the aerosol of tobacco heating systems decreased only by 42.7% compared to 3R4F reference cigarette smoke by and by 33.7 – 40.3% compared to commercial cigarettes smoke, so these products can be a replacement for traditional cigarettes.